FR2857086A1 - Solar drying of bulk sewage sludge, spreads material successively in layers to form moist mass and mixes each layer directly after spreading, with that below - Google Patents

Abstract

The material is spread successively in layers forming a moist mass (M). Each layer is mechanically-mixed (4) immediately after spreading, with the immediately-underlying layer : Layers are formed as strips, mixing (4) being carried out along them. Odd numbers of strips are formed; spreading taking place in one direction on a first, then in the opposite direction on the next, and so on to the end, then back to the first. Mixing forms a swathe. The mass is 0.5-3 m high and several meters wide. It is formed in a glasshouse, with five changes of air per hour. Internal recirculation is 10-50 times per hour. Temperature, moisture and gas content of the air are measured, controlling its replacement rate from the results. The material is sewage sludge. Layers are spread and mixed as described, with a frequency between once an hour and once a week. Between several spreading operations, the mass is turned once. An independent claim is included for the plant carrying out the method.

Description

I Technical field and prior art

  The elimination of sludge, especially in the field of sewage treatment, is becoming increasingly critical (increasing quantities, technical constraints for landfilling more severe, passionate reactions of local residents ....) A technique Especially effective in principle for minimizing sludge volumes is to thermally dry the sludge. The siccities reached are very high (more than 80 to 90% in general). Then, depending on their nature, the dried sludge can be upgraded to incineration as a fuel or in agriculture as a fertilizer, or even simply be landfilled when they are of no interest because of their physicochemical characteristics.

  If, indeed, this technique of thermal drying is simple in principle, it is much less in practice. For example, during drying, the sludge tends to become more and more viscous and it takes large amounts of energy to stir the sludge and transfer heat to the heart of these sludge become very compact. In addition, the temperatures achieved with certain drying techniques are sometimes the cause of fires and high dust levels in the drying gases can cause explosions.

  To take into account these technical constraints, thermal drying plants are relatively expensive in terms of investment and operation (mainly energy costs). This is why this type of technology is only implemented on installations of consistent size.

  For small and medium capacity units, among the various known solutions, there is a simple and economical solution based on the use of renewable and free energy, solar energy. The solution uses air drying by natural means, ie solar drying in a greenhouse.

  In practice, solar drying technologies use the same operating principle: the sludge to be dried is placed in layers more or less thin inside a greenhouse. In order to bring the wet part of the sludge into contact with the ambient air, sludge reversal systems are used to accelerate drying. In patent DE-43 15321 or DE-19836268, a rotating apparatus running on rails brews sludge over the entire width of the pile. Patent US Pat. No. 6,243,968 describes a turntable in the form of a carriage whereas in the case of patent FR-2 789 335, it is a system equipped with plowshares towed in the mud. spread on the ground. EP-0 899 529 discloses an apparatus for mixing sludge randomly on a planar surface.

  In a different field, namely that of the composting of organic waste disposed in windrows, one of the techniques for aerating the product in fermentation is to use a straddle turner. In operation, the frame of this unit is located above the swath and rests on each side on wheels ensuring its advancement. In the lower part, between the wheels, there is a stirring assembly for stirring the fermenting product at the time of passage of the turner. This type has been the subject of various patents (for example, DE-19 636992, EP-0 346 642, EP-0 755 368).

  He. Technical problem and solution.

  These known solutions are generally satisfactory, but deserve to be perfected.

  The object of the invention is to optimize the aeration of the wet material (in particular sludge of purification plant) during air drying by a natural route (without voluntary thermal input), that is to say in practical when drying in a greenhouse, especially by avoiding the formation of a crust (we speak of crusting) on the surface of the swath (which limits the transfers with the outside) and by allowing a frequent renewal of the surface to as well as the contact interface between ambient air and sludge.

  The invention proposes for this purpose a method of solar drying a bulk wet material in which this wet material is spread in successive layers so as to form a wet mass, each layer being, just after spreading, mechanically mixed with the underlying wet mass.

  The invention furthermore proposes a bulk wet material treatment device, adapted to the implementation of the aforementioned method, comprising a dirigible chassis carrying, in the upper part, a sub-assembly of distribution of moist material in bulk adapted to dispense. in layer this wet material on the ground and, in the lower part, a subset of turning comprising a stirring system adapted to stir at least this layer.

  It will be appreciated that, according to the invention, the distribution and flipping of the wet bulk material to be dried is combined, this reversal relating to both the material already being dried and the material which has just been dispensed, which ensures a good mixture and a good drying of the material in all its mass; in addition, a good optimization of the drying surfaces, the handling of the wet material to be dried and the physical phenomena of air drying and aerobic fermentation are obtained.

  The equipment used is inspired, with quite substantial adaptations, from the mechanical equipment of the windrow turner type used in the composting of waste.

  By wet material is meant any natural or non-natural material whose water content (moisture) is substantial, within a very wide range of possible values.

  The present invention may be implemented, in a non-exhaustive manner, on the following wet materials: sludges resulting from water treatment, urban or industrial wastewater treatment (primary sludge, biological sludge, digested sludge, physicochemical sludge and mixed sludge) - waste from agriculture and agro-food industries previously crushed (plants, ....) - inert waste from industrial by-products.

  According to advantageous features of the method of the invention, optionally combined: the layers are formed into elongated strips on which a new layer of wet bulk material is spread and this layer is mixed with the underlying strip, in one direction longitudinally then in the other, which helps to optimize the exchange surface for a given volume of bulk wet material, the layers are formed in an odd plurality of adjacent strips, the spread of each layer being in a first on a first band and then in the opposite direction on the adjacent band, spreading on a band starting near the end of the spread on the previous band, then, after spreading on the last band, a new spreading on the first band in the opposite direction; this allows that, without particular movement of the dispensing and turning equipment, one brews each band in one direction and then in the other, which avoids that in the long run, a band ends up moving longitudinally; of course, an even number is also possible, the mechanical mixing is carried out so as to give the mixed mass a swath form, which also contributes to optimizing the exchange surface for a given volume, - the wet mass has a height between 0.5 m and 3 m and a width of the order of a few meters, which corresponds to realistic dimensional ranges, - the wet mass is formed in a greenhouse whose air volume is renewed at less than 5 times per hour, this volume of air is circulated internally with a rate of 10 to 50 times per hour, preferably between 10 and 30 times, the temperature, the hygrometry and the content are monitored. in predetermined gas of this volume of air and the air change is regulated accordingly, the wet bulk material is formed of sludge and a new layer of this bulk wet material is spread and mixed with the mass underlying a frequency included of the order of once per hour and of the order of once a week, preferably of the order of 1 to 4 times per day, one carries out at least one additional operation of reversal of the wet mass between several stages of spreading a new layer, which helps to prevent slowing of drying between two phases of distribution / flipping of bulk material.

  According to other advantageous features of the invention, this time concerning the device: the reversing subassembly comprises a transverse horizontal rotor provided with projecting arms, the reversing subassembly is shaped so that, after action on a pile on the ground, it has the form of a windrow, the distribution subassembly comprises a tank of wet material in bulk provided at the bottom of a transverse opening of distribution and dosage of this wet material in bulk, - the dispensing opening and dosing is adjustable width, the transverse opening is formed between an edge of a bottom and a lower edge of a wall portion, - this bottom is a treadmill adapted to circulating towards the opening, the lower edge is carried by a movable portion height forming an adjustable door, - it is self-propelled, having two opposite directions in advance, - it is mounted on caterpillars.

  Finally, the invention proposes a solar drying installation of a wet bulk material adapted to the implementation of the aforementioned method, comprising a greenhouse on a sealed area, a treatment device of the aforementioned type io inside this greenhouse , and an automated set of ventilation air drying.

  According to advantageous characteristics, possibly combined: it furthermore comprises a set of internal stirring of the brewing air, the ventilation assembly of the drying air comprises, at the outlet, a chemical treatment or filtering element. of the air, it comprises complementary elements formed on the wet material treatment device in bulk and outside thereof for its guidance along a path inside the greenhouse, it further comprises a system control system cooperating with temperature and hygrometry sensors inside the greenhouse, - the control system is connected to gas sensors adapted to monitor the content of predetermined harmful gases.

III- Description of the invention

  Objects, features and advantages of the invention will emerge from the description which follows, given by way of nonlimiting illustrative example, with reference to the appended drawings in which: FIG. 1 is a block diagram of a processing device of wet material in bulk according to the invention, during implementation of the method of the invention, - Figure 2 is an elevational view of the front side of this device in an exemplary embodiment, - the figure 3 is a side view, along arrow III of FIG. 2, FIG. 4 is a perspective view, FIG. 5 is a schematic diagram of a windrow pile, FIG. 6 is a diagram. In principle, a processing plant for carrying out the process of the invention, represented in a starting phase, is shown in FIG. 7 after treatment of a strip of wet bulk material on the ground. FIG. 8 is a view after treatment of a second strip of this mat FIG. 9 is a view after treatment of all the strips and before further treatment of the first band, FIG. 10 is a view after this new treatment of this first band, and FIG. is a view after new treatment of all bands, before a third treatment of the first band.

  Principle of solar drying In the case of sludges containing fermentable organic materials, the solar drying process of the invention aims to optimize the efficiency of this drying by promoting, during this treatment, the progress of 2 processes known per se : - air drying, - aerobic fermentation which can be analyzed as follows.

  The fermentation of the organic matter is carried out by microorganisms in aerobic medium, that is to say in the presence of oxygen. The reactions that take place during this fermentation are, like any oxidation, exothermic. There is therefore a significant rise in temperature (50 to 60 C), which allows to hygienize the product in fermentation and to dry.

  To perform this fermentation under the best conditions, the sludge to be treated is put into the form of piles (preferably windrows) of a height preferably between 0.5 and 3 m and must be sufficiently porous to allow a good diffusion of the oxygen in the pile. For this, the raw sludge is mixed with a portion of the dried sludge. Regular turning of the product in fermentation ensures good aeration, thus promoting the oxidation reactions and therefore its drying. This reversal also allows, on the one hand, to evacuate the calories produced mainly in the form of water vapor and, on the other hand, to homogenize the fermentation by maintaining the porosity of the treated mixture.

  This fermentation process takes place as long as the sludge is sufficiently moist. Beyond 50 to 60% of dry matter, the fermentation slows down and then stops.

  As for air drying, it is based on the ability of the air to charge with water vapor until it is saturated. In a conventional drying process, drying gases supply energy to the material through exchange with the exposed surface, and it is again through mass exchange with this surface that the drying gases are charged with water vapor that they will evacuate out of the drying system.

  In the case of the invention, it is not these drying gases that provide the energy necessary for the vaporization of water but the energy from solar radiation and the biological oxidation of part of the water. organic material of the product to be dried.

  So, two fundamental and simultaneous principles manage the drying phenomenon: heat transfer to evaporate the liquid on the surface of the solid.

  transfer of material inside the solid to the surface, coupled with the transfer of water vapor to saturate the drying gases.

  To overcome the limiting nature of the diffusion of water in the sludge to the surface, it is therefore useful to renew the exchange surface, and ensure a supply of new material in a uniform layer and thin.

  This is achieved in a particularly efficient manner by the device shown schematically in Figure 1, which ensures both the feeding of elongated piles of wet material to dry and the turning of these piles.

  This device 1 essentially comprises, mounted on a dirigible chassis schematized under the reference 2, in the upper part a subassembly 3 lo distribution of wet bulk material adapted to distribute a layer of wet material on the ground (or on a strip material M already deposited on the ground and being dried), and in the lower part a reversal subassembly 4 comprising a stirring system adapted to stir at least this layer (and the underlying band). It may be noted that, as the device moves to the right (see the arrow pointing to the right), the subassembly 3 is open at its right end, so that the wet material coming out of it (see the dashed line ) is itself returned and mixed with the rest of the underlying band as soon as it is deposited.

  This device is preferably used to dry dewatered municipal sludge. They can be primary, biological, mixed or digested. Solar drying can dry other products mixed with sludge such as fats that provide nutrients during the composting phase and thus reduce the problems of fat treatment.

  But this device can also be used to dry other wet materials such as vegetables, etc.

  As represented in FIGS. 2 to 4, the device shown schematically with reference to FIG. 1 comprises the frame 2, which comprises two lateral walls 2A and 2B intended to laterally run along the pile (not represented), and a horizontal table 2C connecting these side walls.

  Between the side walls is mounted, transversely to the direction of movement of the device, a shaft of the rotor 4, on which are mounted reversing arms 4A, the shape and positioning (here bias) are advantageously chosen (in known manner in itself) to promote the obtaining, after brewing-turning, a generally triangular section of section (see Figure 5).

  This chassis is provided with ground taxiing means, here formed of tracks 6 mounted on a set of motorized or free rollers, here three in number, rotated by a motor of any known type suitable (not shown). As is known, by giving different speeds to the tracks, it is easy to cause a movement to the right or to the left of the device 1.

  Above the table 2C is the device 3 for distributing wet bulk material, typically comprising a reservoir containing wet bulk material and provided at the bottom with a transverse dispensing and dispensing opening 7, in practice in slit shape.

  In the example shown, this opening is of width (it is its smallest dimension, perpendicular to the width of the device) adjustable.

  It is preferably formed between an edge of the bottom 8 of the reservoir and a lower edge 3B of a wall portion.

  This bottom 8 is advantageously movable in the direction of movement of the device, preferably in the form of a moving belt.

  As for the edge 3B it is advantageously arranged on a movable portion forming a trap (here the right wall, in FIG. 4, which can for example slide vertically as a whole, in unrepresented slides 25 formed along the edges of the side walls of the tank).

  The movable bottom 8 and the hatch jointly make it possible to adjust the flow rate of bulk wet material, while the movable bottom makes it possible to regulate the speed of distribution of this material.

  In a variant not shown, this reservoir may be a hopper, in the form of an inverted pyramid, with a distribution slot at its lower end.

  The device 1 is advantageously capable of moving in two opposite directions of advance (thus as well to the right as to the left, in FIG. 3); for this it is sufficient to provide that the motorization of the rollers is reversible; in this case, it is advantageous to provide that each of the transverse walls of the tank can define an opening with the bottom, and that the bottom can move also to the right and to the left.

  Operation: In the example analyzed above, the machine is used during a production cycle combining the functions of long-term storage and actual drying, in the case of sludge drying.

  The cycle can have a variable duration typically ranging from a few months to a year.

  The cycle begins ideally in August to allow to have at the beginning of the period less favorable to the drying (typically late autumn winter) mixed sludge which has a dryness compatible with composting which then completes the little radiation present during these periods. When dried sludge is used in agriculture, this also makes it possible, during one-year cycles (the most frequent case), to empty the installation in July, during which time they can be used directly.

  An installation 10 allowing the implementation of the method of the invention is shown in Figures 6 to 11. It comprises: - A horticultural greenhouse 11 placed on a sealed area. A moderate height peripheral wall (not shown) advantageously protects the structure of the greenhouse during sludge handling.

  > A windrow reversal device such as the device 1 of Figures 1 to 4. By its reversal function, the device ensures the homogenization, aeration and renewal of the drying exchange surface. The device can be automated, semi-automated or manual. By its distribution function, the device ensures the daily or regular supply of fresh product on windrows during drying. This function can be automated, semi-automated or manual.

  - An automated set of drying air ventilation, shown as 12. This ventilation also includes vents at one end of the greenhouse and extractors at the other end of the greenhouse.

  These extractors are for example centrifugal type fans. This set can be regulated on the humidity of the air prevailing inside the greenhouse. This set advantageously offers an average renewal rate of air of 10 greenhouse volumes per hour. This rate of course varies depending on the temperature of the drying air and relative humidity. Depending on the case, the outside air sucked inside the greenhouse can be advantageously preheated so as to increase the efficiency of the installation.

  - Optionally, a brewing air ventilation assembly (schematically referred to as 13) allows a homogenization of the air inside the greenhouse. This set offers a high rate of air mixing: it is between 10 and 50 greenhouse volumes depending on the geometry of the greenhouse (preferably between 10 and 30).

  - Optionally, a set of air treatment extracted on a bio-deodorization filter (for example, preferably that described in our patent FR 2711922) or chemically (schematized under the reference 14). The choice of the treatment method is made according to the nature of the gas to be treated and therefore that of the sludge being dried.

  - Optionally, a set of instrumentation (schematized under the reference 16) used to control the atmosphere inside the greenhouse (temperature, hygrometry) and harmful or explosive gas detectors (CH4 (explosive), H2S; NH3 , etc.), to effectively regulate ventilation and brewing.

  The wet material to be dried is deposited in the greenhouse in the form of a swath (the triangular shape of the windrow offers a larger transfer area than in the case of a horizontal layer for a volume of mud and equivalent width as shown in Fig. 5 where a constant thickness layer configuration is shown in dashed lines for comparison purposes).

  In fact, regularly (every day every week) the new wet material is deposited with our machine on the product being dried.

  The turning device ensures in addition to the distribution of the new wet material to be dried, the mixing, the aeration necessary for the fermentation, the renewal of the exchange surface for drying and the realization of the windrow.

  The sun's rays heat the surface of the windrow which locally causes an increase in the vapor pressure of the water and thus increases the transfer of liquid water material from the sludge to the ambient air in vapor form.

  The ambient air is charged with water. It is used to evacuate water out of the greenhouse. It is therefore used only to transport the moisture taken from the sludge inside the greenhouse to the outside.

  To avoid a phenomenon of saturation of the air in water (which then prevents the drying), one uses fans which make it possible to renew the ambient air of the greenhouse.

  Even at night, without the presence of sun, we dry the mud. It suffices that the ambient air is not saturated and that the surface sludge at the interface with the ambient air contains water in a quantity greater than equilibrium for which we can no longer have transfer.

  The evaporation power varies with solar radiation. Values found in the literature indicate water evaporation capacities of about 800 kg / m2 / year in the north of France up to 1200 1400 kg / m2lan in the southern part.

  The outside surface of the pile is swept by air that is loaded with water. This air is extracted from the greenhouse to ensure sufficient renewal with drier air.

  Moisture-laden air is discharged to the outside by extractors through, for example, autotrophic type deodorization as described in our patent FR 2711922 or by chemical means (such as our process known under the trademark "Aquilair".

  In addition, mixing fans ensure the homogenization of the indoor air to avoid dead zones loaded with moisture.

  As with composting, heaps are returned regularly to substitute dry mud on the surface with moist sludge.

  The operation of the aeration is regulated according to the humidity of the air inside the greenhouse, and the external weather conditions.

  Process management At the beginning of the cycle, the wet material is spread out in the form of strips 2m wide so as to occupy the entire surface of the greenhouse. This operation is performed using a charger, preferably the device of Figures 2 to 4.

  Thus in the spans (commonly called chapels) of 12.60 m, one can realize 5 bands of 2 m wide and in the chapels of 8.0 m one can realize 3 swaths.

  Each day or loading cycle strips with wet material, we add the amount of sludge on the entire surface of the strips using the device 1.

  The turning device returns the tapes several times a day (the number of turnovers varies according to the period, in summer their number will be greater than in winter).

  During the annual cycle, the amount of sludge per band increases, the band thickens but the device 1 gives a swath form to each band.

  The sizing of the greenhouse takes into account the maximum height that the swath can have during a period.

  Thus for a windrow 2 m wide, the maximum height is 1 m (slope angle 45).

  The device 1 is a machine to turn the windrow self-propelled (it can be electric or thermal). It is clear that in the preferred version it will be an electric motor to prevent any escape of exhaust gas in the closed enclosure that is the greenhouse. The drive is in principle carried out by a geared motor; the adjustment of the distribution, aimed at regulating the flow of new product to be discharged, can be manual or motorized.

  This machine makes it possible both to feed the slurry process and to ensure the overturning of the product during drying. Note that the sludge is deposited slightly in front of the machine which allows to perform its mixture in the best conditions, at the same time as the turnaround.

  The machine can be automated, semi-automated or manual. The automation of the machine is essentially based on its

guide.

  Different guidance technologies can be used: É optical systems (laser type).

The GPS.

É the transponder.

  E the wire guide. It is this system that is the preferred version.

  During the first turnaround of the day (Figure 6), the device 1 reversing advance on the first windrow being guided, it practices the reversal of the first windrow. At the end of the windrow (Figure 7) he passes on the second windrow located next to the first swath through transponders. He returns the second windrow and so on with the windrows 3, 4 and 5 (Figure 8). When turning a swath, this windrow moves a little in the direction of the loader.

  In the second turn (FIG. 9), the turner returns to the windrow but in the opposite direction to the first turn, so it tends to move the windrow into its original position before turning.

  Special features of the invention: The method of the invention uses a very special machine, designed both for the windrow of the product to be treated and its turning during drying. This is at least in that the device 1 is different from traditional turners.

  The provision of the swath product is also an originality of the process which has an advantage over known solutions. Indeed, with equal footprint, the exchange surface with drying air is greater in the case of a windrow as shown in the diagram below: In the case of organic sludge, this process promotes the development of aerobic fermentation and drying. The aerobic fermentation phase lasts as long as possible thanks to the maintenance of ideal water conditions.

  The development of aerobic fermentation reactions will allow the rapid increase of temperature and thus promote the evaporation of water even on days of low sunlight and not insignificant hygienization of the product.

Claims (26)

  1. A method of solar drying a wet bulk material wherein said wet material is spread in successive layers so as to form a wet mass (M), each layer being, just after spreading, mechanically mixed (4) with the underlying wet mass.   2. Method according to claim 1, characterized in that the layers are formed into elongated strips on which a new layer of wet bulk material is spread and this layer is mixed with the underlying strip in a longitudinal direction and then in the other.   3. Method according to claim 2, characterized in that the layers are formed in an odd plurality of adjacent bands, the spreading of each layer being in a first direction on a first band and then in the opposite direction on the adjacent band, spreading on a strip starting near where the spreading has ended on the previous band, then, after spreading on the last band, a new spread on the first band in the opposite direction.   4. Method according to any one of claims 1 to 3, characterized in that the mechanical mixing is carried out so as to give the mixed mass a swath form.   5. Method according to any one of claims 1 to 4, characterized in that this wet mass has a height of between 0.5 m and 3 m and a width of the order of a few meters.   6. Method according to any one of claims 1 to 5, characterized in that the moist mass is formed in a greenhouse whose air volume is renewed (12) at least 5 times per hour.   7. Method according to claim 6, characterized in that this volume of air is circulated internally with a rate of 10 to 50 times per hour.   8. A method according to claim 6 or claim 7, characterized in that one monitors (16) the temperature, hygrometry and the predetermined gas content of this volume of air and regulates accordingly the renewal.   9. Process according to any one of claims 1 to 8, characterized in that the bulk wet material is formed of sludge and a new layer of this wet bulk material is spread and mixed with the subsoil. at a frequency between the order of once an hour and the order of once a week.   10. Method according to any one of claims 1 to 9, characterized in that one carries out at least one additional operation of reversal of the wet mass between several stages of spreading a new layer.   l0 11. Apparatus for treating wet bulk material, adapted to the implementation of the method according to any one of claims 1 to 10, comprising a dirigible frame (2) carrying, in the upper part, a subassembly (3). distribution of wet bulk material adapted to distribute a layer of moist material on the ground and, in the lower part, a reversal subassembly (4) comprising a stirring system adapted to stir at least this layer.   12. Device according to claim 11, characterized in that the reversing subassembly comprises a transverse horizontal rotor provided with projecting arms (4A).   13. Device according to claim 11 or claim 12, characterized in that the reversing subassembly is shaped so that, after action on a pile on the ground, it has the form of a windrow.   14. Device according to any one of claims 11 to 13, characterized in that the distribution subassembly (3) comprises a wet bulk material tank provided in the lower part of a transverse opening (7) for distribution and dosing of this bulk wet material.   15. Device according to claim 14, characterized in that the dispensing opening and dosing is adjustable width.   16. Device according to claim 14 or claim 15, characterized in that the transverse opening is formed between an edge of a bottom (8) and a lower edge (3B) of a wall portion.   17. Device according to claim 16, characterized in that the bottom is a treadmill (8) adapted to flow towards the opening.   18. Device according to claim 16 or claim 17, characterized in that the lower edge is carried by a movable portion height forming an adjustable door.   19. Device according to any one of claims 11 to 18, characterized in that it is self-propelled, having two opposite directions in advance.   20. Device according to claim 19, characterized in that it is mounted on caterpillars (6).   21. A solar drying installation of a bulk wet material suitable for carrying out the method according to any one of claims 1 to 10, comprising a greenhouse (11) on a sealed area, a device (1) according to the invention. any one of claims 11 to 20 within said greenhouse, and an automated assembly (12) for ventilating drying air.   22. Installation according to claim 21, characterized in that it further comprises an assembly (13) for internal mixing of the brewing air.   23. Installation according to claim 21 or claim 22, characterized in that the ventilation assembly of the drying air comprises, at the outlet, a chemical treatment element or filtering air (14).   24. Installation according to any one of claims 21 to 23, characterized in that it comprises complementary elements provided on the wet material treatment device in bulk and outside thereof for its guidance along a path inside the greenhouse.   25. Installation according to any one of claims 21 to 24, characterized in that it further comprises a control system cooperating with temperature and hygrometry sensors (16) inside the greenhouse.   26. Installation according to claim 25, characterized in that the control system is connected to gas sensors adapted to monitor the content of predetermined harmful gases.